PlayStation 3D: Performance Analysis

January's CES may have been the breakout event for 3DTV technology, but E3 was a similarly impressive showcase for the new format's gaming credentials. Nintendo 3DS will do more to make 3D a mainstream proposition than anything else to emerge from the games business this year, while at the elite, premium-priced end of the spectrum, PlayStation 3's full-on glasses-based stereoscopic 3D offering can only benefit from the additional exposure.

Sony says that over 15 million 3DTVs will filter into the market this year, and similar to the emergence of 1080p displays we can expect the high-end feature-set to slowly filter down to more affordable price points within 18 months to two years. The question is, how will the current-generation consoles - never designed for 3D - work with the new format?

Digital Foundry recently reported on Sony's presentation to game developers at GDC 2010 in our Making of PlayStation 3D article, describing how existing software either required extensive engine rewrites or compromised performance in order to sustain the creation of two individual images for each eye.

We'll be looking at Sony's existing 3D wares later on in this piece, but what of E3's showcase performance featuring Killzone 3 running in full-on stereoscopic 3D? Putting Guerrilla's game front and centre as the standard bearer for the new display format was a daring move from Sony. The message from the firm was clear: 3D is a priority and our best, most cutting-edge titles will support it. But how?

"When we initially talked to the Guerrilla guys - they're already at 30Hz, they're pushing the system as much as you can push it - they said, 'You want us to do what? You want us to push another entire frame?'" SCEE's Senior Group Director Mick Hocking told us during E3. "But as is the case with engineers, you challenge them to do something like that, put some other game in front of them that's in 3D and in a few weeks they've got it working. There are always ways and means."

The question of how Guerrilla Games has been able to support stereoscopic 3D with Killzone 3 - shaping up as one of the most technologically advanced titles ever created - is perhaps more directly answered when taking a closer look at the E3 3D showing. That footage is available for everyone to see - although the encoding quality is a bit rough, it's contained within the first segment of Sony's own four-part E3 conference vid available to download in HD from the PlayStation Store.

The presentation is intriguing. Obviously it's in 2D, and it appears that Sony has simply shown the perspective from one eye only. The footage suggests heavily that Guerrilla's major compromise with 3D Killzone was in resolution: this video runs at half the horizontal resolution of the 2D game, with the whole image (including HUD) scaled up using the PS3 hardware scaler. Rough encoding quality or not, that doesn't stop our analysis tools having at it as duplicate frames stick out like a sore thumb to our software regardless of image quality.

Sony's PSN presentation of the Killzone 3D demo at E3 seems to use the view of just one eye, so half of the frame-buffer then. This is still more than enough for an impromptu performance analysis of the pre-alpha gameplay.

Assuming that the half-resolution solution is in place and that it's not just an artefact of 3D-to-2D downscaling, this suggests that the biggest challenge facing Guerrilla is pixel throughput: there simply isn't the power there to render that full 1280x1470 framebuffer, certainly not in the current pre-alpha stage of development.

According to Sony's 3D team, the human eye is fine with the lower resolution so long as anti-aliasing is good, and here it's difficult for Guerrilla to improve matters: the Sony Technology Group's MLAA, as seen in LittleBigPlanet 2 and God of War 3, has been implemented. Based on first-hand experience of Killzone 3 from E3, the resolution drop is apparent but the extra dimension offered by the 3D experience certainly adds something valuable to the overall quality of the game. Aside from a somewhat "cardboard cut-out" style of look on explosions and the main view weapon, Killzone 3D is an impressive spectacle.

It is curious to note that processing two sets of geometry doesn't appear to have been a huge concern for Killzone 3, although some E3 attendees did point out more pop-in on the 3D version, suggesting that more aggressive LODs are in place. Sony has released 2D footage of Killzone 3, making a comparison seem tempting. However, based on our direct experience of the demo code at E3, the video available doesn't accurately represent the performance of the game and indeed often seems jerkier than the 3D version: 2D vs. 3D is something we'll have to leave until more mature code is available.

So are the compromises worth it? Based on what we've seen so far, there's no doubt whatsoever that in terms of basic image quality and frame-rates 2D is the way to go. But the difficulty Sony will have in marketing and that we will have in communicating the essence of the game is that 3D offers advantages that go way beyond image quality and do present a tangible advantage to gameplay: depth perception is something we take for granted in everyday life, but offers an extraordinary new dimension to video games and how we play them. In short, yes, it's worth it.